Highly water-absorptive optical material

Abstract

A highly water-absorptive optical material obtained by saponification for hydrophilic treatment of a copolymer composed essentially of: (A) from 2 to 30 parts by weight of a (meth)acrylate polymer having at least one polymerizable group per molecule on an average obtained by copolmerizing (a) at alkyl (meth)acrylate monomer and (b) a monomer having at least two polymerizable groups per molecule, as the main components, and (B) from 70 to 98% by weight of a fatty acid vinyl ester.

We claim: 
     
       1. A highly water-absorptive optical material obtained by saponification for hydrophilic treatment of a copolymer composed essentially of: (A) from 2 to 30 parts by weight of a (meth)acrylate polymer having at least one polymerizable group per molecule on an average obtained by copolymerizing (a) an alkyl (meth)acrylate monomer and (b) a monomer having at least two polymerizable groups per molecule, as the main components, and   (B) from 70 to 98% by weight of a fatty acid vinyl ester.   
     
     
       2. The optical material according to claim 1, wherein the alkyl (meth)acrylate monomer (a) is at least one member selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, trifluoroethyl (meth)acrylate and pentafluoropropyl (meth)acrylate. 
     
     
       3. The optical material according to claim 1, wherein the monomer (b) is at least one member selected from the group consisting of allyl (meth)acrylate, vinyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and dipropylene glycol di(meth)acrylate. 
     
     
       4. The optical material according to claim 1, wherein the (meth)acrylate polymer (A) has (c) a hydrophilic group-containing (meth)acrylate monomer copolymerized with the monomers (a) and (b). 
     
     
       5. The optical material according to claim 4, wherein the (meth)acrylate monomer (c) has a hydrophilic group selected from the group consisting of an alkoxypolyalkylene glycol residue, an amido group, an N-substituted amido group, an amino group, an N-substituted amino group, a carboxyl group, a hydroxyl group and a polyalkylene glycol residue. 
     
     
       6. The optical material according to claim 1, wherein the (meth)acrylate polymer (A) is obtained by copolymerizing from 65 to 99.95 mol parts of the alkyl (meth)acrylate monomer (a), from 0.05 to 5 mol parts of the monomer (b) and from 0 to 30 mol parts of (c) a hydrophilic group-containing (meth)acrylate monomer. 
     
     
       7. The optical material according to claim 1, wherein the (meth)acrylate polymer (A) has a number average molecular weight of from about 5,000 to about 200,000. 
     
     
       8. The optical material according to claim 1, wherein the (meth)acrylate polymer (A) has a number average molecular weight of from 10,000 to 100,000 and contains from 1 to 5 polymerizable groups per molecule on an average. 
     
     
       9. The optical material according to claim 1, wherein the polymer (A) has the formula: ##STR2## wherein each of R 1 , R 2  and R 3  which may be the same or different, is a hydrogen atom or a methyl group, R 4  is an alkyl group, A is a polymerizable group selected from the group consisting of an allyl group, a vinyl group and a (meth)acryloyl group, R 5  is a hydrophilic group, and p, q and r are integers satisfying 0.002≦q/(p+q+r)≦0.05 and 0≦r/(p+q+r)≦0.3. 
     
     
       10. The optical material according to claim 1, wherein the fatty acid vinyl ester (B) is at least one member selected from the group consisting of vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl monochloroacetate, vinyl trifluoroacetate and vinyl trichloroacetate. 
     
     
       11. The optical material according to claim 1, wherein a part of the monomer (B) is substituted by (C) at least one hydrophilic monomer selected from the group consisting of a polymerizable group-containing lactam, an alkoxypolyalkylene glycol mono(meth)acrylate, a (meth)acrylamide, an N-mono-substituted (meth)acrylamide, an N,N-disubstituted (meth)acrylamide, a (meth)acryloyloxyalkylamine, an N-mono-substituted (meth)acryloyloxyalkylamine, an N,N-disubstituted alkylamine, (meth)acrylic acid and a hydroxyl group-containing (meth)acrylate. 
     
     
       12. A contact lens made of the optical material as defined in claim 1.